Something like FT245BM for USB 2.0 ? Parallel -> USB with real USB 2.0 bandwidth ?

rickman <spamgoeshere4@yahoo.com> writes:
> Perhaps someone who designs USB devices can explain this.  I have been
> told by the chip companies that USB 2.0 full speed devices are not the
> same as USB 1.1 full speed.  I have been told that there are operational
> differences, or enhancements I guess is a better term, that a USB 1.1
> full speed device is not automatically a USB 2.0 full speed device.  Is
> that correct?  Does USB 2.0 require new features or modes?  

USB 2.0 has extensions to descriptors and such things.  So a full speed
USB 1.1 device does not necessarily meet the full speed USB 2.0 spec.

In practice, the differences are fairly unimportant.

Eric Smith wrote:
> 
> rickman <spamgoeshere4@yahoo.com> writes:
> > Perhaps someone who designs USB devices can explain this.  I have been
> > told by the chip companies that USB 2.0 full speed devices are not the
> > same as USB 1.1 full speed.  I have been told that there are operational
> > differences, or enhancements I guess is a better term, that a USB 1.1
> > full speed device is not automatically a USB 2.0 full speed device.  Is
> > that correct?  Does USB 2.0 require new features or modes?
> 
> USB 2.0 has extensions to descriptors and such things.  So a full speed
> USB 1.1 device does not necessarily meet the full speed USB 2.0 spec.
> 
> In practice, the differences are fairly unimportant.

Any idea if vendors are claiming 1.1 devices are 2.0 when they don't
actually support these new extentions?  Is that allowed?  

-- 

Rick "rickman" Collins

rick.collins@XYarius.com
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Arius - A Signal Processing Solutions Company
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rickman <spamgoeshere4@yahoo.com> writes:
> Any idea if vendors are claiming 1.1 devices are 2.0 when they don't
> actually support these new extentions?  Is that allowed?  

I don't know if they do it, but it's not allowed.  You have to use
USB 2.0 descriptors to be USB 2.0 compliant.

You do NOT have to support High Speed (480 Mbps) to be USB 2.0 compliant.
Many products have been sold as USB 2.0 without High Speed support, which
was confusing consumers.  This is why they came up with the "USB High Speed
Certified" logo.